1. Field of the Invention
The present invention relates to an inkjet recording head driving circuit, an inkjet recording head, and an inkjet printer. More specifically, the invention relates to an inkjet recording head driving circuit, an inkjet recording head, and an inkjet printer for changing, by means of an actuator such as a piezoelectric vibrator, a volume of a pressure generation chamber filled with an ink, discharging by means of this voltage change fine ink droplets from a nozzle linked to the pressure generation chamber, and recording a character, a graphic, or the like on a recording medium.
2. Description of the Related Art
An inkjet printer is conventionally known that includes an inkjet recording head that, by using an actuator such as a piezoelectric vibrator, changes (expands or contracts) a volume of a pressure generation chamber filled with an ink, and that, as a result of an internal pressure change within the pressure generation chamber, discharges ink droplets from the tip of a nozzle formed to communicate with the pressure generation chamber.
A technique related to a driving circuit that drives such an inkjet recording head is disclosed in, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-179964, a technique for dividing a driving cycle into two cycles, and for supplying to the actuator in time sequence a first driving voltage waveform for discharging ink droplets, and a second driving voltage waveform that while avoiding discharging ink droplets prevents the kind of nozzle clogging which is caused by increase in ink viscosity.
Further, a technique is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2001-26102 (U.S. Pat. No. 6,276,773) for providing plural waveform generation circuits that output plural types of driving voltage waveforms within one printing cycle, for selecting a driving voltage waveform from among various types of driving voltage waveforms according to waveform select data based on gradation data, for supplying the selected driving voltage waveform to the actuator, and for thereby acquiring plural gradations within one driving cycle.
The technique disclosed in JP-A No. 2001-179964 has, however, encountered the following difficulties. It is necessary to transfer print data twice, within one driving cycle, to a section that on the basis of the print data selects one out of the first driving voltage waveform and the second driving voltage waveform, and that supplies to the actuator the driving voltage waveform selected. Such a procedure causes redundant print data, and complicates image processing control. In addition, in order to acquire plural gradations within one driving cycle, it is necessary to supply the actuator with the first driving voltage waveform multiple times within one driving cycle. JP-A No. 2001-179964 describes a configuration in which an inversion circuit is provided that inverts print data at predetermined timings within one driving cycle, thereby making it sufficient to transfer the data only once within one driving cycle. However, one out of the first driving voltage waveform for discharging ink droplets and the second driving voltage waveform for providing meniscus vibration without discharging ink droplets, is invariably selected. Because of this, in the case of a configuration in which plural gradations are acquired, by providing a waveform generation circuit that outputs plural driving voltage waveforms within one driving cycle, and a waveform generation circuit that outputs only one driving voltage waveform within one driving cycle, the technique disclosed in JP-A No. 2001-179964 cannot be applied.
The technique disclosed in JP-A No. 2001-26102 has encountered the following difficulties. It is necessary to transfer waveform select data twice, within one driving cycle, to a switching section that selects one of plural driving voltage waveforms according to waveform select data based on gradation data, and that supplies to the actuator the voltage waveform selected.